The present invention relates to the field of antennas. More particularly, the present invention relates to the method of shaping the azimuth patterns of the radiated beam from the antenna array both for broadcast and receive antennae.
Several approaches may be used to shape the azimuth pattern of the radiation pattern from an antenna. One involves the use of hinged metal reflectors that are grounded to antenna and fastened with heavy bolts. This method is employed outside of the environmental cover of the antenna or radome. Since this method is constantly being exposed to the weather and wind, it must be strong enough to support wind loads. In addition the hinged metal reflectors, being electrically grounded to the antenna, must be securely fastened after adjustment. Also it is important to note that during adjustment the antenna array is unsuited for service due to the intermodulation distortion and electrical noise created during hinged metal reflector adjustment. This noise and signal distortion is due to the intermittent ground path through the metal to metal contact of the hinged attachment of the reflector to the array of the antenna. Another approach uses replaceable reflector brackets which mount to the outside structure of the antenna, that is outside of the radome of the antenna. During replacement of the reflector brackets the subject antenna is unsuitable for service due to the intermodulation distortion and electrical noise created. The replaceable reflector brackets are limited to incremental azimuth angle adjustments and do not offer continuous variability as is available with the hinged metal reflectors.
Producing a incremental azimuth pattern adjustment, however, is too rigid an approach for many applications. An incremental azimuth pattern adjustment solution cannot be altered to fit changing circumstances, and does not allow for optimizing the carrier-to-interference ratio and requires physical presence to make the change. Of the continuously variable azimuth pattern adjustment methods, the hinged metal bracket method produces inter-modulation products, and requires physical presence to make the change. Therefore, existing methods of providing azimuth pattern adjustment, for example using hinged metal reflectors, and replaceable reflector brackets are labor intensive, and so are often unreliable and expensive for the purpose of optimization of the azimuth pattern for the improved performance of the wireless network.
The complexity of the previously described methods stem from the need to be physically present to affect the desired change in the azimuth pattern of the antenna as well as the need to discontinue service of the subject antenna during modification. It is generally known in the art that a receive antenna responds, and is directly related, to a radiation pattern broadcast by the antenna. Thus, the methods associated with azimuth pattern adjustment to a broadcast antenna are applicable to adjusting a receive antenna to improve its reception in a particular direction.
As a result and in light of an ever more competitive environment, it is desirable to manufacture an antenna with the ability to adjust the orientation of the radiated beam. Due to continued cost constraints it is desirable to produce antenna of the most simple design and greatest ease of manufacture.
By the reshaping of the azimuth patterns of the radiated beam the antenna structure of the present invention can remain in operation and new antenna pattern requirements can be fulfilled using the original antenna and thus save the time and expense of replacing the original antenna with another antenna of a different azimuth pattern now needed in the wireless network. An adaptable antenna is desirable as it is simpler to adjust the antenna by actuators for the reorientation of the radiated beam. An adaptable antenna also lends itself to the remote operation of the actuators so as to remove the need to be physically present for the reorientation of the antenna radiated beam.
The present invention is an antenna array which includes a number of antenna elements, being dipoles or other radiating elements being vertically polarized or plus and/or minus 45 degree, or horizontally polarized to the axis of the antenna and electrically floating beam shaping reflectors that by means of precise geometry and movement inside the radome adjust the left and right hemisphere independent azimuth radiation pattern of the radiated beam. The present invention overcomes many of the shortcomings of prior art. Instead of using hinged metal reflectors which are electrically grounded, the present invention employs a light weight electrically floating reflector that is position inside the protective cover of the antenna radome thus allowing the precise continuous adjustment of the azimuth pattern of the antenna by a means of remotely controlled actuators. Being an electrically floating reflector, allows for adjustment to be made during the time the antenna is in service thus eliminating the need to take the antenna out of service to affect the adjustment. Positioning the electrically floating reflector inside the antenna radome also protects the mechanism from the weather greatly reducing contamination of the mechanism. The elimination of metal to metal contact of the electrically floating reflector also greatly reduces the introduction of intermodulation distortion and the generation of electrical noise. Though prior art is referenced, the present invention achieves similar but improved results, is an entirely different method than those that use hinged metal reflectors and replaceable brackets.
An antenna array which includes an antenna array which includes a number of antenna elements, being dipoles or other radiating elements being vertically polarized or plus and/or minus 45 degree, or horizontally polarized to the axis of the antenna and electrically floating beam shaping reflectors according to the present invention is capable of continuously varying the left and right azimuth independent, azimuth of the radiated beam of the radiation pattern associated with an antenna, the radiation pattern comprising an RF signal, the antenna having a plurality of elements and having an element terminal for each element and further having a feed system for communicating the RF signal between each element terminal and a common feed terminal. An antenna beam shaping device according to the present invention includes two electrically floating beam shaping reflectors that by means of precise geometry and movement inside the radome adjust the azimuth radiation pattern, left and right independent, of the radiated beam. It is this electrically equivalent adjustable horizontal aperture by means of the electrically floating beam shaping reflector device which allows the adjustment of the length of the effective horizontal dimension of the antenna which causes for the change in the azimuth radiated pattern of the radiated beam of the antenna.
The electrically floating reflectors due to their shape and relative positions cause the azimuth radiated pattern of the radiated beam to be adjusted in both left and right hemisphere of the radiated beam either in unison or independently in any relationship within the range of azimuth adjustment.